The English Court of Appeal has recently confirmed that the reckless transmission of HIV can amount to a criminal offence, following on from a similar development in Scotland in 2001. This development has led to some concern as to whether doctors could, in certain circumstances, themselves be liable for the onward transmission of HIV by a patient. This article reviews the current scope of the criminal law, before considering the law on liability for onward transmission in the UK. It concludes that civil liability (liability in damages) for onward transmission will be imposed only in unusual cases, and probably only where a doctor has failed to discharge his or her duty of care towards one of his or her own patients. Criminal liability is perhaps theoretically possible but exceptionally unlikely.